1. Field of the Invention
The invention applies to the manufacture of flat tension mask color cathode ray tubes. More specifically, the invention provides means for achieving registration of the aperture patterns of flat tension shadow masks and related cathodoluminescent screens.
In particular, the invention relates to a portion of the process steps employed in the manufacture of the faceplate assembly of a flat tension mask color cathode ray tube. The faceplate assembly includes a glass front panel, a support structure on the inner surface of the panel, and a tensed foil shadow mask affixed to the support structure.
In this specification, the terms "grille" and "screen" are used, and apply generally to the pattern on the inner surface of the front panel. The grille, also known as the black surround, or black matrix, is widely used to enhance contrast. It is applied to the panel first. It comprises a dark coating on the panel in which holes are formed to permit passage of light, and over which the respective colored-light-emitting phosphors are deposited to from the screen.
The holes in the grille must register with the columns of electrons passed by the holes or slots in the shadow mask. This is the primary registration requirement in a grille-equipped tube; the phosphor deposits may overlap the grille holes, hence registration requirements are less precise.
In tubes without a grille, on the other hand, it is the phosphor deposits which must register with the columns of electrons. The word "screen," when used in the context of registration, therefore includes the grille where a grille is employed, as well as the phosphor deposits when there is no grille.
2. Problems in The Conventional Manufacturing Process
Historically, color cathode ray tubes have been manufactured by requiring that a shadow mask dedicated to a particular panel follow the panel through various stages of the manufacturing process. Such a procedure is more complex than might be obvious; a complex conveyer system is needed to maintain the marriage of each mask assembly to its associated panel throughout the manufacturing process. In several stages of the process, the panel must be separated from the mask, and the mating shadow mask cataloged for later reunion with its panel mate.
With the recent commercial introduction of the flat tension mask cathode ray tube, many process problems related to the curvature of the mask and panel have been alleviated or reduced. Necessarily, however, initial production of flat tension mask tubes has been based on continued use of the proven technology of mating a dedicated mask to a specific front panel throughout the manufacturing process. However, because the flat tension mask requires tension forces during the manufacturing process as well as after installation in a tube, somewhat cumbersome in-process support frames become necessary. These frames introduce complexity and expense in the manufacture of color cathode ray tubes of the tension mask type.
Thus the desirability of simplifying the conventional production process remains as great as ever in the manufacture of cathode ray tubes of the flat tension mask type.
It has been recognized that color tube manufacture would be simplified if any mask could be registered with any screen (commonly termed an "interchangeable" mask), so that masks and screens would no longer have to be individually mated. Yet to this day, no commercially viable approach suitable for achieving such component interchangeability has been implemented or disclosed.
3. Known Prior Art
______________________________________ 2,625,734 Law2,733,366 Grimm 3,437,482 Yamada et al 3,451,812 Tamura 3,494,267 Schwartz 3,563,737 Jonkers 3,638,063 Tachikawa 3,676,914 Fiore 3,768,385 Noguchi 3,889,329 Fazlin 3,894,321 Moore 3,983,613 Palac 3,989,524 Palac 4,593,224 Palac 4,692,660 Adler 4,695,761 Fendley FR1,477,706 Gobain GB2,052,148 Sony 20853/65 Japanese ______________________________________
Article "Improvements in the RCA Three Beam Shadow-Mask Color Kinescope," Grimes, 1954, Proceedings of the IRE, January, 1954, pgs. 315-326.